In both bacula_5.0.2.orig.tar.gz/bacula_5.0.2.orig.tar/bacula-5.0.2/ src/lib/sha1.h and in bacula_2.4.4.orig.tar.gz/bacula_2.4.4.orig.tar/ bacula-2.4.4/src/lib/sha1.h it mentions that the file cannot be modified.

Also, the file sha1.c has no licensing information itself, referring back to sha1.h so I assume that the restriction of not being able to modify it also applies to sha1.c as well.